Oscillating and amplifying vacuum tube for very short waves



Oct. 14, 1952 J. P. VOGE 2,614,234

OSCILLATING AND AMPLIFYING VACUUM TUBE FOR VERY SHORT WAVES Filed Jan. 31, 1947 2 SHEETSSI-IEET l Oct. 14, 1952 J. P. VOGE 2,614,234

OSCILLATING AND AMPLIFYING VACUUM TUBE FOR VERY SHORT WAVES Filed Jan. 51, 1947 2 SHEETS-SHEET 2 1,, l I I I I 5 4 Patented Get. 14, 1952 OSCILLATING AND AMPLIFYING VACUUM TUBE FOR VERY SHORT WAVES .iiean iaul Voge, Paris France Application January 31, 1947, Serial No. 725,682

' In France February 2, 1946 1 This invention relates to improvements in oscillating and amplifying vacuum tubes for very short waves and more particularly to those tubes which make use of the time of travel of the electrons between the various electrodes of the tube, i.e. tubes of the transit time type.

According to the present invention there is provided an electron tube for very short waves, comprising in combination two resonant cavities constituted by wave guide sections oscillating in a system of standing waves, and a cathode producing a beam wide enough so that, upon passage of said beam through the guide sections in a direction transverse to the length of the guides and with the width dimension of the beam substantially parallel to the length of the guides, the width of the beam will extend along the length of the guides by at least the distance between two adjacent maxima of the standing waves in the said guide sections, i. e. a distance equal to at least half of a wave length in the standing wave pattern in the guides. The tube of the invention further comprises means for establishing electrical and magnetic fields adapted to cause the guides to be traversed by the electron beam at right angles to the long axis of the guide sections, and means for exciting the cavities. The first cavity traversed by the beam may be referred to as the buncher cavity and the second as the catcher cavity, in accordance with the terminology now accepted in the art.

Preferably the buncher cavity and the catcher cavity are constituted by right cylindrical guide sections short-circuited at their ends, disposed parallel to each other and provided with electronpermeable grids to allow the electron beam to pass through.

These grids have, parallel to the length of the generators of the cavities, a length equal to an integral multiple of the half wave length of the standing wave pattern in the guides, and the electron beam passing through the cavities therefore passes through an electric field alternating in a standing wave pattern, the beam having such a width that its width extends lengthwise of the cavities an integral number of half wave lengths.

This arrangement provides a tube capable of operating over a wide band of frequencies at high eificiency.

The invention will now be described in terms of a number of preferred embodiments by reference to the accompanying drawings in which:

Fig. 1 is a vertical cross-section and Fig. 2 a

4 Claims. (Cl. 315--6) corresponding horizontal cross-section of a velocity modulated tube according to a preferred embodiment of the invention, diagrammatically illustrated, the vacuum envelope, heating filament, and input and output coupling loops beingomitted for simplicity.

Fig. 3 is a view similar to that of Fig. 1 but showing a modified form of tube according to the invention.

Fig. 4 is a vertical section illustrating in further detail a tube of the type shown in Figs. 1 and 2.

Fig. 5 is a horizontal section of the in Fig. 4; and

Fig. 6 is a plan view of the base of the tube of Fig. 4, seen from below;v

Referring to Figs. 1, 2 and 3, a cathode 1 (heating element not shown) is disposed in a vacuum envelope (not shown) with its long dimension parallel to the length, i. e. to the generators, of

tube shown two resonant cavities 2 of cylindrical shape dis posed centrally of the tube. The term cylindrical is to be understood in its broad geometrical sense as defining a surface generated by a straight line or generator moving parallel to itself while maintaining contact with a plane curve or directrix, the generator being perpendicular to the plane of the clirectrix. A collector electrode 4 is disposed parallel to the cathode on the opposite side of the cavities 2. The cavities 2 take the form of two similar adjacent hollow wave guide sections of. H-shaped cross section,

the webs or bars of the cross sections being 00-' cupied by electron-permeable grids 3 to allow the electron beam to pass through. The cavity adjacent the cathode is the buncher," and the other is the catcher. The electrons flow from the cathode to the collector electrode in'the direction a in Fig. 2, at right angles to the generators of the cavities. The length of the guide sections which form the cavities 2 is so chosen that the standing wave represented by the sine shaped curve in Fig. 1 corresponds to one wave length of the standing wave pattern. The field within the cavities is such that at any instant the variation, along the length of the generators, of the component of the field between the modulating and collecting grids is, perpendicular to the grids. The spatial variation is therefore along the directionaofFigZQ... Q,

A single beam (Fig. l) or 'a plurality of beams (Fig. 3) may be propagated transversely of the generators of the cavities. Particularly interesting results are obtained if the electron-permeable grids are so disposed over the height of the cavities that at their ends, to which correspond the edges of the beam, there exist nodes of the standing wave pattern.

The most favorable case corresponds to a single beam passed through the cavities perpendicular to their generators and having a width equal to one wave length of the standing wave pattern within the cavities, as illustrated in Fig. 1.

In Figs. 4, and 6 a complete embodiment of the invention is shown. In those figures I designates the cathode, H the heater filament, E2 the focusing electrode, 2| the buncher cavity, 22 the catcher cavity, 3| the grids in the buncher and 32 the grids in the catcher, and 4 the collector electrode. 5| is the coaxial input line for high frequency energy, and 52 is the coaxial output line for the withdrawal of high frequency energy. As shown, the buncher and catcher cavities are of the same length and support systems of standing waves one wave length long. The electron-permeable grids 3| and 32 extend over the entire height of the cavities, and the cathode l is of equal length, generating an electron beam having a width equal to the length of the grids. The beam passes through the cavities perpendicularly to their generators.

Fig. 6 shows the arrangement of the base of the tube of Fig. 4, the reference characters applied to the pin terminals in Fig. 6 being the same as those applied to the tube electrodes with which they respectively connect.

While the invention has been described in terms of a number of preferred embodiments, these embodiments are exemplary only, the scope of my invention being set forth in the appended claims.

What I claim is:

1. An electron discharge device of the velocity modulation type comprising two cavity resonators cohstit ted by sections of wave guides shortcircuited at their ends and adapted each when suitably excited to support a system of standing waves whose half wave length is an integral submultiple of the length its wave guide, the wave lengths of said standing wave systems being substantially equal, and two electron-permeable grids arranged on opposite faces of each of said guides, each of said grids having a length substantially equal to an integral multiple of one half of said common wave length.

2. An electron discharge device of the velocity modulation type comprising two cavity resonators each formed by a right cylindrical section of a wave guide short-circuited at its ends, said wave guides being adapted each to support therein a system of standing waves one wave length long having nodes at the ends of the guide, said guides being of equal length, each of said guides having formed on opposite faces thereof an electron-permeable grid extending over the entire length of the guide on which it is formed, a cathode and a collector electrode each having a length substantially equal to the length of said guides, said guides, cathode and collector electrode being supported parallel and opposite each other with the guide sections between the cathode and collector electrode, means to couple energy into the guide adjacent the cathode, and means to couple energy out of the guide adjacent the collector electrode.

3. An electron discharge device comprising two cavity resonators each conforming to a right section of a wave guide having an H-shaped cross section and short-circuited at its ends, said guide sections being of the same length, each of said guides having over its entire height electron-permeable grids on its faces Whose directrixes are the opposite sides of the H-bar, and a cathode and a collector electrode having lengths substantially equal to the length of said guides, said cathode being adapted to emit a ribbon-shaped electron beam having a width equal to the height of said guides, said cathode. guides and collector electrode being supported parallel with said cathode, grids and collector electrode in line whereby said beam may pass from said cathode through said guides perpendicular to their height and emerge to the collector electrode.

4. An electron discharge device of the velocity modulation type comprising two cavity resonators each formed by a right section of a wave guide of cylindrical shape short-circuited at its ends, each of said guides being adapted to support a system of standing waves or" the same wave length an integral number of half wave lengths long with nodes at the ends of the guides, an electron-permeable grid formed on each of two opposite faces of each of said guides, said grids having a length equal to an integral number of halves of said wave length, each of said grids having its ends spaced an integral number of said half wave lengths from the ends of the guide on which it is formed, a straight cathode having the same length as said grids, said cathode being adapted to generate a ribbon-shaped beam of electrons having a width equal to the length of said grids, a straight collector electrode having a length equal to the length of said grids, and means to support the cathode, guides and collector electrode parallel with the guides between the cathode and collector electron and with the cathode, grids and collector electrode in line, whereby upon the application of a suitable potential difierence between the cathode and guides an electron beam will be accelerated through said guides with its width parallel to the length of the guides.

JEAN PAUL VOGE.

REFERENCES CITED The followin references are of record in the file of this patent:

UNITED STATES PATENTS 

